Unless otherwise indicated herein, approaches described in this section are not prior art to the claims listed below and are not admitted as prior art by inclusion in this section.
Firearms such as AR15 rifles include an upper receiver and a lower receiver, which are typically engaged near a barrel location upon assembly with pivot and takedown pins. The pivot pin and takedown pin mainly provide the function of securing the upper and lower receivers together for normal use of the firearm. For purposes of maintenance such as cleaning, lubricating, or customizing parts of such a firearm, however, a user is typically required to disassemble the upper and lower receivers from each other by removing at least the takedown pin or both the takedown pin and pivot pin.
The pivot pin and the takedown pin need to be inserted into apertures in the upper and lower receivers of the firearm to assemble the lower receiver and upper receiver to each other. For the pivot pin, typically a corresponding detent pin needs to be inserted inside a chamber of the lower receiver, wherein the pivot pin depresses an associated spring underneath the detent pin as the pivot pin laterally slides into a pivot pin aperture on the lower receiver. For the takedown pin, the takedown pin is typically inserted into a takedown pin aperture first. Then, a corresponding detent pin and an associated spring are inserted inside another chamber of the lower receiver, whereby an end plate (or a receiver) depresses the spring and the detent pin as a castle nut tightens the end plate onto a buffer tube of the firearm. However, for both pivot pin and takedown pin, assembly and disassembly tend to be difficult for a user due to the opposing force that each spring associated with the pivot pin and takedown pin exerts. This is due to the protruding force exerted by the spring often impedes assembly and disassembly processes and causes problems for many users such as losing springs or pins if such small parts are not properly aligned.
Moreover, traditionally, many users follow tedious steps and require special tools such as Clevis pins in order to handle pins during assembly and disassembly of the upper receiver and the lower receiver of a firearm. Even with fancy tools that are solely dedicated to deal with the pivot and takedown pins, it is still tedious and time consuming for the user. Besides, traditional pivot and takedown pins have a single track where all three small parts of the spring, the detent pin, and either the pivot pin or the takedown pin need to be carefully guided and aligned simultaneously at one point during assembly and disassembly. Otherwise, inconvenience and frustration may result (e.g., the detent pin could take into the air due to spring compression).
There are pins that simplify disassembly and assembly processes using a magnet, but such pins in the market still do not solve issues such as inconvenience in disassembly that requires a tool to depress the detent pin each time. With existing and current configurations of pivot pins and takedown pins, it tends to be difficult for a user to switch the pins from a locking position to a release position easily and quickly in order to separate the upper and lower receivers that are joined together by the pivot pin and takedown pin.